10 April 2011
It’s been an interesting week or so in the climate science arena with papers on climate change in the AGU journal Geophysical Research Letters and Nature. Then there’s that study put together by Dr. Richard Muller to “check” the temperature rise that NOAA/NASA and the Hadley Centre (UK Met. Office) have reported. If you’re still in the rapidly dwindling group of those who think we are not facing a very serious problem, then you aren’t going to like any of it.
The most fascinating to me was the paper in Nature, by two German scientists who looked at the effects that jet contrails are having on our climate. It’s been known for a long while now that the contrails left by thousands of high altitude flights a day have an effect, but this paper has come up with what looks like some solid numbers. It seems that the warming from these man-made cirrus clouds is actually greater than all the CO2 produced by the jet engines!
Someone once told me that I was all wrong about climate change, because if the Earth got warmer, more clouds would form and block the sunlight. Oh, if it were that simple! High thin clouds (like cirrus) actually cause warming, because they let short wave radiation in, but do a much better job of blocking the invisible IR radiation from escaping. Clouds are still one of the tough problems in climate change, and John Cook at Skeptical Science has a quick summary here.
The whole issue is even more complicated by the fact that these man-made cirrus clouds cause fewer of the natural cirrus clouds to form, so to add up the effect, you have to take it all into account. The paper is very readable (and free in this case) even for those who do not know the lingo of climate science. Perhaps, the biggest surprise is the linear jet contrails you see in the sky are not the main cause of the net warming. It’s the very thin (and spread out) cirrus cloud that forms from the contrails, and lingers for hours at the very top of the troposphere.
The other paper is regarding the often stated goal by many countries (based on the overwhelming opinion of the science community) to keep the warming of the planet under two degrees. It now appears that this is virtually impossible. Here is a quote from the abstract of the paper:
“The results of this study suggest that limiting warming to roughly 2°C by the end of this century is unlikely since it requires an immediate ramp down of emissions followed by ongoing carbon sequestration in the second half of this century.”
Some more tidbits:
In the past, well-known physicist Dr. Richard Muller has made some comments that are quite skeptical of climate science. He put together a (rather heavily criticized) group to check the independent results of NASA/NOAA and the Hadley Centre . The climate change is a hoax crowd were all a flutter over this and declared the truth would finally come out. Well, it did but Paul Krugman (author of Hot Flat and Crowded and holder of a Nobel prize) tells the story much better than I could.
Another study (in GRL) is about the rate of sea level rise due to the melting icecaps in Greenland and Antarctica. Eric Rignot (who has done ground breaking research in the field) and others used two independent methods to estimate how much ice is being lost and what the rate of increase is. Here is a snippet from the Abstract.
Here, we present a consistent record of mass balance for the Greenland and Antarctic
ice sheets over the past two decades, validated by the comparison of two independent techniques over the last
8 years: one differencing perimeter loss from net accumulation, and one using a dense time series of time variable
gravity. We find excellent agreement between the two techniques for absolute mass loss and acceleration of
mass loss. In 2006, the Greenland and Antarctic ice sheets experienced a combined mass loss of 475 ± 158 Gt/yr,
equivalent to 1.3 ± 0.4 mm/yr sea level rise. Notably, the acceleration in ice sheet loss over the last 18 years was
21.9 ± 1 Gt/yr2 for Greenland and 14.5 ± 2 Gt/yr2 for Antarctica, for a combined total of 36.3 ± 2 Gt/yr2. This
acceleration is 3 times larger than for mountain glaciers and ice caps (12 ± 6 Gt/yr2). If this trend continues, ice
sheets will be the dominant contributor to sea level rise in the 21st century.
In case you missed it, the melt rate in Greenland and Antarctica is increasing by 36.3 gigatonnes per year.